Clinical Problem:In the practice of anesthesiology, great care must be taken to positionpatients properly for endotracheal intubation. This includes extending andflexing the patient’s neck and lifting the head to visualize the vocal chords byaligning the pharyngeal and laryngeal axes (Fig. 1), achieving what is knownas the sniffing position. Such positioning becomes difficult when patientsare overweight or have excess tissue around their necks, posing the risk ofsoft tissue collapse which can fully obstruct view of the vocal cords. Tocombat this issue ramped position is indicated to open the chest and allowexcess tissue to fall back. While multiple devices exist to aid in reachingthese positions, they are ignored in lieu of towels and linens (Fig. 2). Notonly is this system imprecise, but it forces the care team to manually lift andposition patients. This poses the risk of improperly positioning the patientfor intubation which can lead to stroke risk, nerve/brain damage, or evendeath and puts the medical staff in risk of musculoskeletal injuries arisingfrom excess strain.

Need Statement:

An adjustable mechanism is needed to safely and certainly position the upper body of patients for intubation.{ }

The IntuBed: Upper Body Positioning for Surgical IntubationCole Haugen, Emily Hein, Leah Novik, Clare Peine

BMEn 4002W Senior Design ∙ Group 16: AnesthesiologyAdvisors: Dr. Steven Saliterman, Dr. Kevin Wang

University of Minnesota – Twin Cities, Minneapolis, MN

Market Gap & Goals

Clinical Background & Need Studies and Results

Market Background:• Intended users: anesthesiologists and certified nurse anesthetists

performing intubations on severely overweight to obese patients• 42 Million+ procedures requiring intubation in the US alone

• Comorbidities associated with common surgical causes often stemfrom excess weight

• Adverse outcomes can yield longer hospital stays at $2,300/night, withthe potential of $100,000s more in bills depending on severity

• $1 Billion+ Forecasted market size for surgical beds in the US by 2022 with3.9% annual growth

Current Solution Limits:• Solutions include gel head donuts/rings, foam blocks, a ramp under the

patient, and a jaw elevation device→ Multiple options yet towels and linens are mostly used in the operating

room. Why?• Current solutions aren’t adjustable, segmented, or precise, still require

physical labor, and cannot be easily removed for surgery→ These limitations form the basis of the requirements for The IntuBed

Project Goal:• To create a stand-alone system that can adequately lift and lower a

patient incrementally at the flip of a switch, thus providing a safe and effective way to achieve proper positioning during surgical intubation

Proposed Solution

Figure 5: Device-controlling switchboard.

• High pressure air tank• Pressure decreased by regulator

• Airflow reaches manifold• Air to bladders controlled via

inlet solenoid valves by user• Air moves into 1-3 bladders until

reaching hydrostatic equilibrium or until valve is closed by user→ Patient is lifted

• Air flows out once switch flipped down to open outlet solenoids• Bladder moves from high

pressure to lower atmospheric room pressure

→ Patient is lowered

Segmented MechanicallyAdjustable

No Physical Labor

Diverse Precise

• Material: 8-gage Polyvinyl chloride (PVC)• Compliant, water-resistant, inert

• Edges heat-sealed• ¼” quick-connect and nut fastener

form dual inlet/outlet• Able to withstand weighted cyclic

strain• Dimensioned to fit the head,

shoulders, and upper back of a 1.741 m male

Figure 3: Schematic of device operation and airflow.

Figure 1 a-b: a. The sniffing position, demonstrating the alignment of the laryngeal and pharyngeal axes b. Schematic of a patient in a ramped position with reference to 0 o.

Validation

Manifolds• Material: Anodized aluminum• Dimensioned to fit three solenoids

• Excess ports plugged with stainless steel NPT bolts and thread tape → prevent air leaks

• Functions as a diverter from one air inlet to three outlets

Solenoids• Specs: 24V/2A, up to 120 PSI• Electric current passes through a

coil of wire, inducing a magnetic field• This pulls the pin of the valve

open, allowing for air flow

• 3D printed PLA filament• 3-way switch controls each bladder

• Up→Inflation. inlet opens• Down→Deflation, outlet opens• Middle→Closed, inlet/outlet

closed• Switch closes circuit loop to allow

solenoid to draw current from power source

Figure 5a-c: a. Manifold and solenoids tethered into the baseboard of the device b.

Detached manifold c. Detached solenoid

A

B C

Figure 4a-b: Bladders in fully a. deflated and b. inflated states.

A

B

A B

A B

Finite Element Analysis Model: To determine ideal material and thickness for bladder fabrication.

Measured AnglesNeck Torso

Base: 47.5o Base: 140o

Raised: 56o Raised: 144.5o

B

A

Figure 7: Male subject a. before and b. after elevationwith the IntuBed. Dashed lines represent a. the angle fromthe back of the head to the end of the chin and b. theangle from the bottom of the arm to the highest point ofthe chest. Angles were measured using a protractor.

Displacement Angle Measurement: To verify capability of system to adjust axes of patient alignment.

Figure 6 a-b: a. COMSOL rendering of inflated head bladder with simulated weight on top b.Maximum bladder thickness vs. displacement for 8-gage material. Linear regression showsmaterial response is very similar, PVC can be chosen for its enhanced properties.

Biocompatibility Assessment:To ensure inertness of nylon overlay on bare skin during the surgical window.

Figure 8 a-d: a. 50x50 mm nylonpatch as taped onto patient’sforearm for 24 hours b-c. Subjects 1and 2 (female and male) afterremoval of patch – no irritationvisible or reported. d. Subject 3(female) after removal of patch –irritation visible and reported.

0

0.5

1

1.5

2

2.5

3

InflateShoulder

Return toNeutral

DeflateShoulder

InflateHead

Return toNeutral

DeflateHead

InflateBack

Return toNeutral

DeflateBack

Res

po

nse

Tim

e (s

)

Average User Response Times

Cyclic Testing: To examine limits of bladder design under repeated use.

Bladder Fate After 50 Cycles

Head

Shoulder

Back Failure Mode: Tearing of material by quick connect, add nylon washer to mitigate

Failure Mode: N/ABladder able to withstand cyclic strain

Failure Mode: N/ABladder able to withstand cyclic strain

Table 1: Summary of cyclic testing of inflatable bladders. Head and shoulder componentswithstood 50 full inflation/deflation cycles, back component failed at cycle #32.

AcknowledgementsThank you to Dr. Steven Saliterman and Dr. Kevin Wang for their mentorship and support throughout this project, to the Medical Devices Center for opening their space, materials, and equipment for prototyping, and to the departments of Anesthesiology and Surgery for the opportunity to shadow their work and receive feedback throughout the design process.

This project is funded by a grant from the National Science Foundation.

Future Directions

Use In Operating Room• Integrate soft base pad and tethering mechanism to operating table• Test inflation with operating room air line

Upgrades • Use smaller solenoid valves to decrease energy demands• Explore use of pressure sensors for closed-loop feedback to prevent

excess pressure in bladders• Survey other bladder fabrication materials for increased longevity

Expand Applications • Develop dimensions and adjust specs for a broader range of sizes,

expanding market to slimmer patients and children• Examine potential market expansion opportunities: sleep apnea,

spine pain & neuropathy, third-world & emergency medicine

Figure 9: Validation of device usability from three test users. Users with no priorintroduction to the IntuBed were given a series of commands and response time wasrecorded. The decreasing time trend indicates that users were able to quickly intuit themethod of operation.

Clinician Feedback:

• Auditory input of valves opening/closing

• Addition of back bladder to lift entire torso

• Clean design

• High power drain• Lack of pressure sensors• Electronics close to patient

Δ

ConclusionsThe IntuBed is successful in lifting patients in a manner that adjusts thereference axes of the head and neck while pushing the chest out and torso up.This allows for excess tissue to fall back towards the lower body, opening thevisual field for endotracheal intubation. Not only does this system mitigate therisk of patient injury from improper intubation, but also provides clinicians analternative to manually lifting and positioning a patient. Compared to currentdevices, the IntuBed provides greater control over upper body position and canbe left underneath the patient during the course of the surgery while providingpadding and support supplemental to the operating table, making the IntuBedan attractive alternative to what is available on the market.